EU slaps initial sanctions on Russia

Ukraine's Prime Minister Arseniy Yatsenyuk waves as he arrives for an EU summit at the EU Council building in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Geert Vanden Wijngaert)
The Associated Press

Ukraine's Prime Minister Arseniy Yatsenyuk waves as he arrives for an EU summit at the EU Council building in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Geert Vanden Wijngaert)

Ukraine's Prime Minister Arseniy Yatsenyuk arrives for an EU summit at the EU Council building in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Michel Euler)The Associated Press

Ukraine's Prime Minister Arseniy Yatsenyuk arrives for an EU summit at the EU Council building in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Michel Euler)

Ukrainian soldiers guard the military base at the Black Sea port of Sevastopol in Crimea, Ukraine, Wednesday, March 5, 2014. A special U.N. envoy visiting Crimea was threatened by 10 to 15 armed men on Wednesday and ordered to leave the region, where Ukraine and Russia are locked in a tense standoff. (AP Photo/Darko Vojinovic)The Associated Press

Ukrainian soldiers guard the military base at the Black Sea port of Sevastopol in Crimea, Ukraine, Wednesday, March 5, 2014. A special U.N. envoy visiting Crimea was threatened by 10 to 15 armed men on Wednesday and ordered to leave the region, where Ukraine and Russia are locked in a tense standoff. (AP Photo/Darko Vojinovic)

From left, European Commission President Jose Manuel Barroso, Ukraine's Prime Minister Arseniy Yatsenyuk, European Council President Herman Van Rompuy and European Union High Representative Catherine Ashton participate in a meeting during an EU summit in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Olivier Hoslet, Pool)The Associated Press

From left, European Commission President Jose Manuel Barroso, Ukraine's Prime Minister Arseniy Yatsenyuk, European Council President Herman Van Rompuy and European Union High Representative Catherine Ashton participate in a meeting during an EU summit in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Olivier Hoslet, Pool)

From left, Polish Prime Minister Donald Tusk, French President Francois Hollande, British Prime Minister David Cameron, German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi speak with each other during a meeting at an EU summit in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Michel Euler, Pool)The Associated Press

From left, Polish Prime Minister Donald Tusk, French President Francois Hollande, British Prime Minister David Cameron, German Chancellor Angela Merkel and Italian Prime Minister Matteo Renzi speak with each other during a meeting at an EU summit in Brussels on Thursday, March 6, 2014. EU heads of state meet Thursday in emergency session to discuss the situation in Ukraine. (AP Photo/Michel Euler, Pool)

German Chancellor Angela Merkel speaks during a media conference after an EU summit in Brussels on Thursday, March 6, 2014. European Union leaders are holding an emergency summit to decide on imposing sanctions against Russia over its military incursion in Ukraine's Crimean peninsula. (AP Photo/Michel Euler)The Associated Press

German Chancellor Angela Merkel speaks during a media conference after an EU summit in Brussels on Thursday, March 6, 2014. European Union leaders are holding an emergency summit to decide on imposing sanctions against Russia over its military incursion in Ukraine's Crimean peninsula. (AP Photo/Michel Euler)

European Council President Herman Van Rompuy gestures while speaking during a media conference after an EU summit in Brussels on Thursday, March 6, 2014. European Union leaders are holding an emergency summit to decide on imposing sanctions against Russia over its military incursion in Ukraine's Crimean peninsula. (AP Photo/Virginia Mayo)The Associated Press

European Council President Herman Van Rompuy gestures while speaking during a media conference after an EU summit in Brussels on Thursday, March 6, 2014. European Union leaders are holding an emergency summit to decide on imposing sanctions against Russia over its military incursion in Ukraine's Crimean peninsula. (AP Photo/Virginia Mayo)

BRUSSELS (AP) — BRUSSELS — The European Union suspended talks with Russia on a wide-ranging economic pact and a visa agreement Thursday in response to its military incursion into Ukraine's Crimean Peninsula, threatening tougher sanctions unless Moscow swiftly defuses the crisis.

The moves at an emergency EU summit came on the heels of visa and financial sanctions the Obama administration imposed on Russians and Ukrainians over the military incursion into Crimea.

EU President Herman Van Rompuy said further measures could include travel bans, asset freezes and the cancellation of an EU-Russia summit if Moscow does not quickly end its aggression and joins meaningful, multilateral talks within days to halt the crisis.

"We are in close coordination with the United States on this," German Chancellor Angela Merkel said. "We cannot go back to business as usual" with Russia, she added.

However, the EU's latest sanctions appeared weak compared to the U.S. ones and to what some more hawkish EU countries wanted, particularly those bordering Russia. Poland's leader noted the resistance to penalizing Moscow remains fairly high among some members of the 28-nation bloc because of Europe's close proximity, energy dependence and trade ties to Russia.

As the EU leaders met, the U.S. also sent six F-15 fighter jets to Lithuania to bolster air patrols over the Baltics, and a U.S. warship is now in the Black Sea to participate in long-planned exercises.

The sanctions on both sides of the Atlantic aimed to rein in Europe's gravest geopolitical crisis in a generation, which developed swiftly again Thursday with Crimean lawmakers declaring their intention to split from Ukraine and join Russia instead and scheduling a referendum in 10 days for voters to decide the fate of the disputed peninsula.

Visiting the summit, Ukraine's Prime Minister Arseniy Yatsenyuk branded the referendum illegitimate. "Crimea was, is, and will be an integral part of Ukraine," he told reporters.

In Washington, President Barack Obama said the referendum would violate international law.

The EU put on ice talks on a wide-ranging economic agreement and on granting Russian citizens visa-free travel within the 28-nation bloc, a goal that Moscow has been pursuing for years.

The decision followed tough negotiations among member states divided over how to react to the Russian aggression.

"Not everyone will be satisfied with the decision, but I should say that we did much more together than one could have expected several hours ago," said Polish Prime Minister Donald Tusk.

Tusk said there was "no enthusiasm" in Europe for sanctioning Russia, but he called the moves inevitable, given the country's blatant violation of international rights by its actions in Crimea.

British Prime Minister David Cameron agreed, while acknowledging that stiffer sanctions would not only hurt Russia.

"Of course there are consequences for Britain if you look at financial services. Of course there are consequences for France if you look at defense. Of course there are consequences for some European countries if you look at energy," he said.

But he said the EU had to take tough action to counter what he called "the most serious crisis in Europe this century."